Transmission or manipulation of voice signals in applications that have limited bandwidth or memory typically results in tradeoffs that reduces quality in the resultant voice output signal or reduces flexibility in the manipulation of such acoustic signals. The speeding up or slowing down of music or speech using time-scale modifications (that preferably does not alter the pitch) has many applications including dictation, voice mail, and sound track editing to name a few. Another particular application, voice message paging is not economically feasible for large paging systems with current technology. The air time required for a voice page is much more than that required for a tone, numeric or alphanumeric page. With current technology, voice paging service would be economically prohibitive in comparison to tone, numeric or alphanumeric paging with less than ideal voice quality reproduction. Another constraint in limiting voice message paging is the bandwidth and the present methods of utilizing the bandwidth of paging channels. In comparison, the growth of alphanumeric paging has been constrained by the limited access to a keyboard input device for sending alphanumeric messages to a paging terminal, either in the form of a personal keyboard or a call to an operator center. A voice system overcomes these entry issues since a caller can simply pick up a telephone, dial access numbers, and speak a message. Further, none of the present voice paging systems take advantage of Motorola's new high speed paging protocol structure, also known as FLEX.TM..
Existing voice paging systems lack many of the FLEX.TM. protocol advantages including high battery saving ratios, multiple channel scanning capability, mixing of modes such as voice with data, acknowledge-back paging (allowing for return receipts to the calling party), location finding capability, system and frequency reuse, particularly in large metropolitan areas, and range extension through selective re-transmission of missed message portions.
With respect to the aspect of paging involving time-scaling of voice signals and to other applications such as dictation and voice mail, current methods of time-scaling lack the ideal combinations of providing adequate speech quality and flexibility that allows a designer to optimize the application within the constraints given. Thus, there exists a need for a voice communication system that is economically feasible and flexible in allowing optimization within a given configuration, and more particularly with respect to paging applications, that further retains many of the advantages of Motorola's FLEX.TM. protocol.